Author: ryan.bloomgren

My portable USB phone charger’s LCD screen broke today, so i decided to tear it apart and use its 11,200 mAh battery for the server UPS. I also recently built a 3D printer, so I designed a case to hold  the components to my budget Ebay UPS.

I decided to refine the schematic the same for the USB UPS, because the boost converter was prone to dropping out early, and therefore the battery was never 100% usable.

The new schematic uses a TP4056 1A Lithium Ion charger with a DW01 Battery protection IC and the MT3608 DC-DC boost converter (capable of boosting a voltage as low as 2V up to 5V with 2A of output current). 3A rectifier diodes and a large capacitor are used to smooth the transition between mains sourced 5V power and battery power.

The whole circuit can be assembled for less than $8. (The high quality super capacitor being the most expensive part)

In testing, the Mini-Sever can now run for just shy of 4 hours off of mains power.

I built a UPS using a an EBay sourced boost converter and lithium ion charge controller. I used a lithium ion battery I salvaged out of an old bluetooth speaker. I mounted it all to a sheet of aluminum. Total cost: $3

I used a 3.3v signal from the power supply to tell the pi if it lost AC power. I modified my software to E-Mail me and shutdown the pi if the battery got too low.

In testing the UPS, I uncovered that at a certain point, about half charge on the battery, the voltage dips and the boost converter drops-out triggering a reset on the pi. I only end up getting around 20 minutes of battery life with the 750 mAh battery, which is adequate for most power loss events.